diff --git a/tests/MockDelegateFunctionBuilderTest.php b/tests/MockDelegateFunctionBuilderTest.php
index 1aaef23..0d040a0 100644
--- a/tests/MockDelegateFunctionBuilderTest.php
+++ b/tests/MockDelegateFunctionBuilderTest.php
@@ -89,7 +89,7 @@ public function testBackupStaticAttributes()
      *
      * @return array Test cases.
      */
-    public function provideTestBackupStaticAttributes()
+    public static function provideTestBackupStaticAttributes()
     {
         return [
             [],